The field of passive location by TDOA techniques is very vast; the procedure proposed by [1] may be cited in particular. The latter proposes a measurement which is performed on the basis of signals arising from several single-channel stations. The source of interest can then be located in two dimensions by intersection of hyperbolas with the aid of a minimum of three single-track receivers. This technique entails solving systems of non-linear equations and resorts to a procedure of linearized least squares requiring initialization close to the real position of the emitter so as not to diverge. Moreover, time synchronization of all the receivers is necessary as well as the use of a data merging center. Finally this technique is not very robust in a multipath situation and in the presence of interference. The articles [2][3] propose TDOA techniques making it possible to separate the sources on the basis of a priori knowledge of their cyclic characteristics.
Location techniques based on TDOA/FDOA measurements have been developed, in particular that cited in [4] in the case where the emitter and/or the receivers are in motion. This procedure makes it possible to reduce the useful number of receivers, but still requires synchronization.
The field of AOA estimation and location in the presence of multi-paths with the help of a multi-channel receiving station is very vast; in particular [5] may be cited.
AOA/TDOA joint estimation has generated a large number of references; for example [6] may be cited. In contradistinction to the TDOA-estimation-only procedures, the processing operations performed here are done with multi-channel receiving stations. However:                the objective is to carry out the parametric analysis of a channel with multi-paths from a single emitter E1 to a multi-channel receiving station at A1. The jointly estimated parameters are then the angles of arrival θ11j and the time gaps τ11j−τ11j′ between the paths of this same emitter due to reflectors at Rj and Rj′.        the joint estimation of the parameters (θ11j, τ11j−τ11j′) is very often envisaged on the basis of the knowledge of a pilot signal.        
Thus in [6], the authors propose a procedure for estimating the angles of arrival and the delays of the correlated multipaths of a source received on an antenna array. The problem is modeled by a spatio-temporal matrix parametrized by the angles and the delays sought. The propagation channel is first of all estimated blindly or with the aid of reference sequence, and then, the parameters are estimated. This technique has, however, the drawback of making assumptions about the signal emitted; it is thus assumed that the signal is digital and modulated by a known waveform. Moreover, it involves a channel estimation procedure which does not perform source location.
The state of the art closest to the invention relates to single-station location (SSL) techniques used within the framework of High Frequency (HF) transmissions. The field of HF SSL is very vast; reference [7] may be cited for example. Location is done with the aid of a single multi-channel receiving station. The reception of a path reflected off the ionosphere, coupled with the knowledge of the model of the ionosphere (altitudes of the layers), makes it possible to calculate the position of the emitter. In certain approaches, propagation delays are estimated between several paths reflected off the various layers of the ionosphere, thus circumventing the need for perfect knowledge of the model of the ionosphere in order to perform location. However, these procedures then assume that the reflections off the layers occur in the middle of the emitter/receiver distance. Moreover the drawback of these procedures is that they assume a priori knowledge of the ionosphere.